1. Field of the Invention
The present invention relates to a fluid-cooled heat sink for electronic components and a process for making the heat sink.
2. Description of the Related Art
As is well known, heat sinks are devices used to lower the temperature of electronic components and circuits by dissipating the heat these components and circuits produce during operation.
Heat sinks may be of the liquid-cooled type. These are also known as liquid cooling plates and are used when the heat transfer system is required to be much more efficient than systems based on air cooling, whether by natural or forced convection.
Liquid-cooled heat sinks usually include a dissipating element through which a cooling liquid is passed so that the liquid comes into contact with the electronic component to be cooled. The heat transferred from the component to the dissipating element is absorbed by the flowing liquid which carries it away. Liquid-cooled heat sinks known to prior art may comprise a single plate-like element made of a highly conductive material, usually metal. The plate has a plurality of through holes made in it with a precision tool. The holes are made in several directions to create a network of intersecting channels. The ends of most of the holes are then sealed to form a path through which the cooling liquid is made to pass.
Besides heat sinks of this type, there are also liquid-cooled heat sinks made, for example, by embedding a set of coil-shaped metal tubes, in a metal plate having a set of matching milled grooves to receive them. Lastly, there are heat sinks consisting of an aluminium or copper plate, in which the grooves are milled, and a cover positioned over the plate and sealed by gluing, brazing or screwing.
All the heat sinks mentioned above are made by removing material using precision machine processes. The manufacturing of heat sinks of this kind involves considerably complex processes. Indeed, these precision processes require the use of complex numerically controlled machines operated by skilled personnel. Also, the number of pieces made per unit time is limited and production speed is limited since each component must be machined individually. Moreover, machine processes where material is removed result in a large amount of waste material which cannot be re-used in the production cycle.
Prior art also teaches the use of extrusion to make a liquid-cooled heat sink comprising a single dissipating plate made by extrusion and having a set of parallel through holes. The holes are then sealed and the channels joined at defined points to form a path for the cooling fluid. This method of making heat sinks of this type also has disadvantages. The material sliding against the sides of the extrusion matrix may cause scoring which leads to loss of essential mechanical properties. This means that the extrusion process must be closely controlled. Special attention must be given to the temperature of the material and the extrusion rate, that is to say, the speed at which the extruded product feeds out of the matrix. The production speed is therefore limited not only by the speed of the extrusion process but also by the fact that each single part must be machined individually to seal the holes to make the path for the cooling liquid. Thus, in this case, too, the process does not lend itself to large series production.
The present invention therefore has for an aim to overcome the above mentioned disadvantages.
The invention has for an aim, in particular, to provide a fluid-cooled heat sink that can be entirely series-produced without requiring individual machining by skilled personnel on one or more of its parts.
Another aim of the present invention is to provide a fluid-cooled heat sink that is easy to make.
Yet another aim of the present invention is to provide a fast and economical process to make heat sinks of the type mentioned above.
The above-mentioned technical need and aims are substantially fulfilled by a fluid-cooled heat sink comprising a first metal plate having a first face and a second face; the first metal plate being associated to at least one electronic component at least along the first face, a second plate having a first face and a second face, the first face of the second plate being joined to the second face of the first plate, at least one groove for a cooling fluid made in the first face of the second plate; means of connection between the first plate and the second plate. This heat sink is characterized in that the first face and the second face of the second plate are parallel to each other at least along the length of the groove.
The above mentioned technical need is also accomplished by a process of forming a first metal plate having a first face and a second face, forming a second metal plate having a first face and a second face, forming in the second plate a groove through which a cooling liquid can pass, and joining the first face of the second plate to the second face of the first plate in such a way that the groove faces the first plate. The process is characterized in that the step of making the groove consists of forming the groove on the second plate by plastic deformation.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.